The present invention is generally directed to an improved RF tag and an apparatus for manufacturing the same. The present invention is more particularly directed to an RF tag including a flexible substrate having formed thereon a transmitter for transmitting a predetermined identification code and a planar electrode structure coupled to the RF transmitter and adapted to receive an electrolyte to form a battery for powering the RF transmitter. The manufacturing apparatus is arranged to mass produce the RF tags on a continuous web basis. The present invention is still further directed to a dispenser for activating and dispensing the RF tags one at a time at a point of use.
RF tags find many different applications ranging from security applications such as electronic article surveillance to detect theft in retail outlets to manufacturing applications such as factory process control to provide information on work completed, parts pedigree, or test data. For security control, rather simple RF tags are employed which transmit RF energy at a single frequency. For manufacturing control, rather sophisticated RF tags may be employed which provide both read and write functions.
Although RF tags are used for a broad range of applications, their penetration into many markets has been limited by at least three factors: tag price; tag size; and tag range. Tag price is dependent upon the number and cost of components used on a tag including the cost of a power source such as a battery which may be required to power many of the components. Tag size is dependent upon the size of a required battery or by the size of a transponder which converts incident RF energy into electrical energy to power the tag. Tag range is dependent upon the output power of a tag reader for tags which derive their electrical energy from the reader through RF coupling and/or upon the capacity of a battery on the tag. Hence, as can be seen from the foregoing, the penetration of RF tags into many markets is largely dependent upon battery characteristics such as cost, size, and capacity.
Current RF tags are presently generally available in three basic forms. These include: passive RF tags; active tags without a battery; and active tags with a battery.
Passive RF tags generally contain a resonant tuned circuit capable of resonating at a single frequency. When the tag is brought into an RF field, it absorbs energy at its resonant frequency. A reader senses the absorption to detect the presence of the tag. Such systems are commonly used for the aforementioned anti-theft detection in retail outlets. These systems are generally short-range systems and generally provide one bit of information corresponding to the single resonant frequency.
Active RF tags without a battery generally contain a small transmitter that derives power from an antenna on the tag that absorbs RF energy transmitted from the tag reader. Energy absorbed by the antenna on the tag is fed into a rectifier bridge and is converted into a DC voltage which is used to power the transmitter on the tag. Although these tags have many advantages over passive tags, they still have limited range due to the small amount of power available through RF coupling from the reader. These tags also suffer from non-uniform range and performance which varies considerably depending upon the operating environment of the tags and the orientation of the tags relative to the reader. All of these factors effect the amount of energy the tag captures from the reader. For tags that are both electrically writable and readable, write range is typically much shorter than the read range because the energy required for programming memory devices is much higher than the energy required for reading.
Active RF tags which include a battery generally solve the problem of limited range and non-uniform performance. The main disadvantage of this type of tag is that generally, only conventional battery energy sources are available which exhibit high cost and size. This limits the utility of active RF tags with a battery since many applications, as for example airline baggage tracking applications, require only a very short tag operating life. RF tags for such applications do not require the amount of power provided by conventional batteries. Further, RF tags for such an application must be relatively thin so that the tags can pass through printers. Unfortunately, conventional batteries do not exhibit such thin dimensions. Lastly, RF tags for such an application must be extremely inexpensive allowing such tags to be disposable after a single use.
From the foregoing, it can be seen that the RF tagging art requires a new and improved RF tag and battery which is of low cost and low profile. Additionally, the battery of such an improved RF tag must be capable of providing sufficient power to power the RF tag active components. However, such a battery should be tailored for providing sufficient power for required, albeit short, periods of time and for a necessary number of read cycles.
The RF tag and power source battery of the present invention provides such an improvement to the art. The RF tag of the present invention can be configured to be very thin given the configuration of the improved battery power source. The battery power source is a planar configuration formed on a tag substrate which may be extremely thin and flexible. The battery generally includes first and second patterns of conductive material formed on the substrate to form the planar electrode structure including an anode structure and a cathode structure coupled to the active components of the RF tag. When necessary, such as, for example, at a point of use, electrolyte may be applied to the electrode structure to complete the formation of the battery for powering the active components of the RF tag and thus, activating the RF tag. The electrolyte may be applied to selected portions of the electrode structure to provide the RF tag with an operating life which is tailored to a given application. Further, the active components may vary from a single-bit transmitter to sophisticated read-write devices rendering flexibility and adapting the RF tag for use in virtually every possible RF tag application.
The RF tag substrate may be formed of inexpensive material. Further, the electrode structure may be formed from inexpensive and environmentally friendly material rendering the RF tags disposable after a single use. Since the RF tag substrate is preferably of flexible material, the apparatus for manufacturing the RF tags is capable of mass producing the RF tags on a low cost, continuous web, reel-to-reel basis.